In an ink jet printer, there is a tendency during printing for ink to mix with dust and paper fibers and dry on the printhead surface surrounding the nozzles, thus interfering with ejection of ink from the nozzles. This problem may be at least partially solved by providing a wiper which extends into the path of travel of the printhead which wipes ink from the printhead surface surrounding the nozzles as the printhead is moved back and forth relative to the wiper.
The wiper may be disposed in a maintenance or service station located to one side of the record feed path. In some cases, the wiper is fixedly mounted at a height such that it extends through the plane of the feed path. In other cases, mechanisms are provided for moving the wiper into an operative position.
In some printhead maintenance mechanisms used in ink jet printers, either each color of the printhead has a separate maintenance assembly or, if all of the colors are housed in one printhead and the monochrome (usually black) housed in another printhead, the two printheads each have a separate maintenance assembly. This is typically the case regardless of whether the color printhead and the black printhead reside in the printer at the same time or if the two printheads are interchangeably mounted on a single printhead carrier.
Some efforts have been made to clean the wiper of removed excess ink and contaminants, so that the wiper can remain effective in cleaning the surface surrounding the nozzles. Such efforts, such as that disclosed in U.S. Pat. No. 5,202,702, are typically directed at providing a protrusion, or raised portion, of the head holder or printhead body which then engages the wiper blade to clean the surface of the wiper. Such protrusions extend substantially perpendicular to the direction of wiping.
Other efforts directed to cleaning a printhead wiper include providing a wiper well, or cavity adjacent to the area surrounding the printhead nozzles so as to remove and collect the excess ink and contaminants that have accumulated on the wiper. This design, however, contributes to increasing the decibel level of the noise generated during a wiper cleaning operation due to the wiper abruptly contacting, or "slapping", the sidewall of the cavity as the wiper enters the cavity. This "slapping" action also creates the risk of inadvertently throwing the removed excess ink and contaminants onto the print media.
In attempting to avoid the above-identified problems, ribs arranged parallel to the wiping direction have been incorporated to bridge across the cavity thereby preventing the wiper from fully entering into the cavity, and abruptly contacting a cavity sidewall. Such a configuration, however, contributes to uneven wear of the wiper, since a portion of the wiping surface of the wiper does not contact at least one of the ribs during a cleaning pass.
Therefore, a need exists for improved means for cleaning excess ink and/or contaminants from a printhead wiper.